Motorized mechanism



April 1942- R. s. CRAIG 2,280,062

MOTORI ZED MECHANISM Filed Dec. 11, 1959 2 Sheets-Sheet l 17 8\ l 8% c HI 55 1a s2 5 BI Q/ SI 85 Fig. 2 inventor Robe-r1- 5. Craig attorneyVALVE STEM April 21, 1942.

R. S. CRAIG MOTORI ZED MECHANISM Filed Dec, 11, 1939 2 Sheets-Sheet 2 LIH8 ,IBZ

I80 mm jimxnfor "Robe-r1 ,8. Craig attoxneg Patented Apr. 21, 1942MOTORIZED MECHANISM Robert S. Craig, Robbinsdale, Minnu assignor toMinneapolis Honeywell Regulator Company, Minneapolis, Minn., acorporation of Delaware Application December 11, 1939, Serial No.308,674

15 Claims.

The present invention is concerned with a motorized mechanism and moreparticularly one adapted to position a member movable between a safefirst position and an active second position.

In many instances it is desirable to utilize a motor to position adevice which is movable between a safe normal position and an activeposition. Thus one typical instance is that of a motorized valvecontrolling the flow of gas to a gas burner or the flow of other heatingfluid to a heating apparatus. In-such a case, the valve is biased toclosed position to insure the return 01' the valve to this position inthe event of power failure. Another type of device of this character isa switch which is active only when it is closed. It is desirable in caseof failure of the switch actuating mechanism for the switch to be movedto its circuit open or its safe position. The present invention isconcerned with an arrangement wherein a motor positions such an element,the arrangement being particularly adaptable to the positioning of avalve.

An object of the present invention is to provide an arrangement whereina motor moves a member to an active position wherein it is retained by aholding means separate from the motor, the transmission means betweenthe motor and the positioned member being thereafter returned to thestarting position so that upon release of the holding means, the memberis free to return by suitable biasing means to its safe normal position.

Another object of the present invention is to provide, in an arrangementwherein a motor moves a member from a safe position to an activeposition and a holding means separate from the motor retains the memberin its active position, transmission means between the motor and themember including a pair of separable links and means for separating thelinks after the member has been moved to active position, so that uponrelease of the holding means, the member is free to return by suitablebiasing means to its safe normal position.

A further object of the present invention is to provide such anarrangement wherein the positioned member is a valve blasted to closedposition.

A still further object of the invention is to provide an arrangement ofthe type mentioned in the previous objects wherein the motor iscontinuously operated until the transmission mechanism has been returnedto its starting position.

A still further object of the invention is to provide an arrangementsuch as set forth abovein which the motor moves the positioning elementto its active position where it is retained by the holding means and isthereupon deenergized and a biasing means is employed to return thetransmission mechanism to its starting position.

A still further object of the present invention is to providearrangements such as set forth above in which the holding means iselectrically operated and is energized by the same source of power asthe motor.

Other objects of the invention will be apparent from a consideration ofthe accompanying specification, claims and drawings of which:

Figure 1 is a schematic view of a preferred form of the invention,

Figure 2 is a schematic showing of a modification of one of the detailsof the arrangement of Figure 1, and

Figure 3 is a schematic view of a modified form of the invention.

Referring to the drawings for a more detailed understanding of theinvention, the system is shown in Figure 1 in connection with thepositioning of a valve. The valve is provided with a valve housing Illhaving an inlet connection it and an outlet connection l2, Extendingthrough the valve body is the usual transverse partition wall M which isapertured at it to provide a valve seat upon which the valve disc l6seats. A spring l'l biases the valve disc 16 into engagement with itsvalve seat. Secured to the valve disc 16 is a valve stem IS.

A motor 20 is provided for moving the valve disc to its open positionagainst the action of biasing spring ll. The motor 20 is shown as beingof the induction type, having a rotor 2| and a field winding 22. Themotor is connected to a reduction gear train generally indicated by thereference numeral 24. The gear at the low speed end of this gear trainis designated by the numeral 25. Secured to gear 25 is a shaft 26 andaxially aligned with shaft 26 is a second shaft 21. Secured to shafts 26and 2? are crank arms 28 and 29, the crank arms being connected by a rod30. At the outer end of shaft 21 is a cam 3|. The motor 20 is sodesigned that upon energization of the field winding 22, the gear trainis rotated in a direction such that gear 25 and shafts 26 and 21 arerotated in a clockwise direction. The cam 3i is shown in the positionwhich it normally assumes when the valve is closed. The radius of thecam gradually increases in a counter-clockwise direction up to its highpoint 33. The cam surface immediately drops down to an arcuate portionextending from point 34 to point 35. This portion of the cam is ofuniform radius for reasons to be pointed out hereinaiter. Projectingfrom the valve stem I8 is an arm 31 which engages the cam 3| and acts asa cam follower. It will be obvious that as the cam 3| is rotated in aclockwise direction from the position shown, the valve stem 3 will beraised until the cam follower 31 leaves the high point 33 whereupon thevalve stem, unless otherwise restrained, is free to drop to the positionshown in which position it remains throughout the rest of the revolutionof the cam.

A spring 40 has one end secured to the rod 33. This spring 40 serves tooppose the action of the motor during the valve opening portion of thecycle and is effective to aid the motor after the high point 33 of thecam has left the cam follower 31.

It will be recalled that in the previous paragraph it was stated thatthe valve stem, after the cam follower 31 has passed over the high pointof the cam, would be free to return to the position shown unlessotherwise restrained. Suitable means are provided for normally holdingthe valve stem in valve open position when moved to this position. Thismeans comprises an electromagnet 45 which cooperates with an armature 46secured to the upper end of valve stem [8. The electromagnet 45 isprovided with a winding 4? in the conventional manner. When the valvestem is moved to its uppermost position by the action of cam armature 46is firmly moved into engagement with the electromagnet 45. Means areprovided for energizing the electromagnet at this stage of the cycle sothat the electromagnet is normally able to maintain the valve in openposition as will be described latter. A thermostat 5|] is provided forcontrolling the operation of the valve. It is to be understood that anyother control switch can be utilized. The thermostat as illustrated,comprises a bimetallic element M to which are secured contact arms 52and 53 which engage with contacts 54 and 55, respectively. Contact arm52 is less widely separated i'rom contact 54 than contact arm 53 is fromcontact 55. The bimetallic element 5i is so arranged that it moves thecontact arms 52 and 53 to the left upon a temperature fall as indicatedby the legends on the drawing wherein the letter C represents cold andthe letter H represents hot. Upon a fall in temperature, due to theunequal spacing of the contact arms from the contacts, contact arm 52will engage contact 54 and upon further fall in temperature contact arm53 will engage contact 55. Energization of the motor is furthercontrolled by a maintaining switch generally designated by the numeral58. This switch comprises a pair of switch blades 59 and 60. The blades59 and 60 are secured to an insulated block 6|. The blade 60 has acurved upper portion 62 forming a cam surface cooperating with an arm 63of insulating material secured to the valve stem l8. Upon upwardmovement of valve stem [8, the arm 53 engage the curved portion 62 ofswitch blade 60 and moves switch blade 60 into circuit making engagementwith switch blade 59. I

Energization of the'motor is further controlled by a cycling switchmechanism including a pair of cooperating switch blades and H. The

switch blade 10 has an upwardly projecting portion 13 which cooperateswith a pin 12 concentrically carried by the gear 25. When the gearportion H of switch blade 14 to hold switch blade 10 in its lowermostposition. A pin 14 of insulating material carried by the valve stem l8cooperates with the switch blade ll. When the valve stem is in valveclosed position, as shown, the switch blade 1| is engaged by pin I4 andheld in its lowermost position wherein it contacts switch blade 10 evenwhen this switch blade is depressed by engagement of pin '12 withportion H thereof, as previously described. Both switch blades 10 and Hare biased upwardly.

A step down transformer I! is provided for the purpose of supplying lowvoltage power for the operation of the motor and its control system.This transformer comprises a line voltage primary winding 18 and a lowvoltage secondary winding 19. The line voltage primary '18 is connectedto line wires 80 and BI leading to a suitable source of power (notshown).

Operation of species of Figure 1 As previously indicated, the variouselements are shown in the position occupied when the valve is closed.This is the position which they assume when the temperature to whichthermostat is subjected is at or above the desired value. Upon a drop intemperature, switch blade 52 is first moved into engagement with contact54. This, by itself, results in the establishment of no energizingcircuits. Upon a further drop in temperature, switch blade 53 is movedinto engagement with contact and. the following energizing circuit iestablished to the field winding 22: from the upper terminal ofsecondary '19 through con-- ductor 83, contact 54, contact arm 52,contact arm 53, contact 55, conductors 84 and 85, field f winding 22,conductor 86, switch blades 10 and 3i results in the valve stem beingmoved upward- 25 is in the position shown, a pin 12 engages the lytowards valve open position. While the upward movement of valve stem itpermits switch arms M to move upwardly, this does not result in thecircuit being interrupted since the initial movement of gear 25 alsomoves pin 12 away from the upwardly projecting portion 13 of switchblade l5 so as to allow this switch. blade to follow switch blade 1 lAfter an initial upward movement of valve stem it has taken place, thearm 63 engages the inclined portion 62 of switch blade 60 to move switchblades 59 and 60 into contact making engagement. The result is that thefollowing maintaining circuit is established to field winding 22: fromthe upper terminal of secondary 79 through conductor 83, contact 54,contact arm 52, bimetallic element 5|, conductor 9|, switch blades 60and 59, conductors 92, 93, and field winding 22, conductor 86, switchblades 10 and H and conductors 81 and 88 to the other terminal ofsecondary '19. It will be noted that this new circuit to field winding22 is independent of contact arm 53 and contact 55. It is this contactarm and contact which are the last to be engaged and are consequentlythe first to be disengaged. Thus it is assured that upon initialengagement of both pairs of contacts the motor will continue to remainenergized even though one set of contacts is immediately thereafterseparated. In this way, an appreciable temperature differential isrequired between the successive operation of the device so thatchattering or excessively frequent operation is avoided.

Upon engagement of both contact arins 52 and 53 with their respectivecontacts 54 and 55, an energizing circuit is established to the winding41 of electromagnet 45. As soon as switch blades 50 and 53 are movedinto engagement, 9. maintaining circuit is established to the winding41. Since this maintaining circuit is established before it is necessaryfor the electromagnet to become active, it is only necessary to considerthis maintaining circuit which is as follows: from the upper terminal ofsecondary 13 through conductor 33, contact 54, contact arm 52,bimetallic element conductor 3|, switch blades 30 and 59, conductors 32and 95, winding 41, and conductors 36 and 83 to the other terminal ofsecondary 19. Since winding 41 is energized independently of contact 55during the initial movement of the valve. it is assured that whenarmature 46 is moved into engagement with electromagnet 45,

the electromagnet will be effective to retain the armature in engagementtherewith. There is no positive connection between the cam 3| and thepin 31 so that as soon as the high point 33 of cam 3| passes the pin 31the valve stem is under the sole control of magnet 45. The motorcontinues to rotate until the gear train returns to the position shownat which time pin I2 engages the upwardly projecting portion I3 ofswitch blade I0 to move this blade to its lowermost position. Sinceswitch blade II has moved upwardly by reason of the upward movement ofpin I4 and since this pin is still in this uppermost position by reasonof the valve stem being held upwardly by the electromagnet 45, switchblades and II will no longer be in engagement when switch blade 10 ismoved to its lowermost position. The result is that the switch blades I0and II are separated at this point to terminate energization of thefield winding 22. It will be seen that the cam 3| and the pin 31constitute a pair of separable links, and that after the high point 33of cam 3| passes pin 31, the links are separated in such a manner thatthe valve is free to return to its closed position upon release by themagnet 45.

The valve disc I5 is held in open position as long as electromagnetremains energized. This will continue as long as contact arm 52 of thethermostat is in engagement with contact 54. Switch 58, connected inparallel with contacts 53-55, is closed. Therefore separation ofcontacts 53 and 55 does not affect the energization of electromagnet 45.As soon as the contact arm 52 separates from contact 54, the winding 41of electromagnet 45 will be deenergized so as to permit the biasingspring I1 to move the valve abruptly to closed position.

The maintaining circuit previously described, including contacts 5254and switch 53, prevents the opening of contacts 53-55 from causingimmediate deenergization of solenoid 45 and consequent closure of valveI6. An appreciable differential is thereby provided between thetemperature at which contacts 5355 close, causing the valve to open, andthe temperature at which contacts 52-54 open, causing the valve toclose. This temperature differential prevents erratic operation of thevalve because of chattering thermostat contacts either due to vibration,or from other causes.

gasburner in accordance with the need for burner operation as indicatedby the temperature to which the thermostat is responsive. In this field,it is essential that if there is a power failure, the valve will bemoved to closed position. It will readily be seen that where the normalcycle is completed, the valve is under the sole control of theelectromagnet and obviously any power failure results in immediateclosure of valve disc I6. liIt is always possible, though unlikely, thatsuch a power failure might occur during the opening cycle and in such acase, if some other means than motor 20 were not provided for actuatingthe gear train 24, the cam 3| might be left in intermediate positionwherein the valve would be held in a partially open position. The spring40 is provided for guarding against such a contingency. The spring 40,acting through the crank arm formed of crank arms 28 and 29 and rod 30tends to bias the gear 25 and cam 3| in a counter-clockwise directionduring the initial portion of the operating cycle. As the valveapproaches open position the moment arm exerted by spring 40 isincreased due to the fact that the crank arms 28 and 29 tend to approacha position more nearly transverse to the direction of pull of spring 40.Before the crank arms 28 and 23 have revolved to the dead centerposition, the high point 33 of cam 3| has moved from underneath the pin31 so that even if a power failure resulted in the cam 3| remaining inthis position, the valve could completely close. As pointed outpreviously, the radius of the cam surface is constant from point 34 topoint 35 so that when the cam is in any position wherein the camfollower 31 would engage this portion of the cam surface, the valve canmove to completely closed position.

It will be seen that I have provided an arrangement wherein a motor isemployed to drive a valve to open position, leave it under the controlof a holding means and then to return the gear train and the variousother elements of the connecting mechanism to the starting position. Inthis way it is assured that the valve will always be free to close upontermination of the holding effect of the holding means. It will furtherbe noted that I have provided means whereby the valve may be safelyclosed in the event of a power failure at any time during its operatingcycle.

M odification of Figure 2 In Figure 2, there is illustrated a slightlymodified form of holding means which may be employed with the valve ofFigure 1. In the arrangement of this figure, an electromagnetic latch isemployed in lieu of a plain electromagnet. Such a latch has theadvantage that it is capable of holding a considerably greater load forthe same number of ampere-turns in the electromagnet. The valve stem inthis figure is designated by the numeral IOI. It will be understood thatthis valve stem is identical in function and arrangement to the valvestem I8 of Figure 1 with the sole exception that instead of an armaturebeing secured at the upper end thereof, the valve stem is provided witha notch I02. A pivoted latch I03 has a nose portion I04 which is adaptedto extend into the notch I02 and retain the valve stem against downwardmovement. Secured to the horizontal arm of the pivoted latch I03 is anarmature I04 which cooperates with an electromagnet I05. The latch I03is pivoted about a pivot I06 and is biased clockwise by a spring I00.The electromagnet I when energized overcomes the effect of spring I08 tomaintain the latch in its latching position. As soon as theelectromagnet s deenergized however the spring I08 is effective torotate the latch I03 in a clockwise direction to move the nose I04 outof the notch I02 and permit downward movement of the valve stem IOI. Itwill be understood that the electromagnet I05 is connected into thecircuit in the same manner as magnet 45 of Figure 1 and that theoperation of this system is in all other respects identical to that ofFigure 1.

Species of Figu 3 In Figure 3 I have shown a modified form of myinvention. In the arrangement of this figure, a motor is effective tomove the valve in cooperative relation with a holding means as in thespecies of Figure 1. Unlike the previous species, however, a biasingspring is effective to return the motor and its connecting mechanism tothe starting position.

Referring to the specific structure of Figure 3 the valve is generallydesignated by the reference numeral II5, this valve is provided with avalve stem H6. The valve is similar in construction to the valve ofFigure 1 so that upward movement of valve stem II6 causes the valve tobe moved to open position and downward movement of stem II6 causes thevalve to be closed.

A motor I is employed for positioning the valve. This motor comprises arotor IN and a field winding I22. The rotor IN is connected through areduction gear train comprising a gear I26 at the low speed of the geartrain. A pin I21 projects, outwardly from the gear I26 and is adapted tocooperate with a hook I 28. The hook I20 is pivotally secured. at I29 toa lever I30 pivotally supported by a pivot pin I32. The lever 930extends through an elongated eye portion I34 at the upper end of valvestem H6. The motor I20 is so designed as to cause clockwise movement ofgear I26 upon energization of the motor. Upon such clockwise movement,the pin I21 engages the hook I28 and rotates the lever I30 in aclockwise direction. This results in the lever I30 moving valve stem II6upwardly.

A coil spring I33 is associated with the lever I30 for returning thetransmission mechanism to its starting position. The spring I33 ispositioned about the pivot pin I32. One arm of spring I33 engages a pinI38 secured to lever I30 and the other arm enga es a fixed pin I39. The

result is that spring I33 exerts a force tending to rotate lever I30 ina counter-clockwise direction.

An electromagnet I40 is provided for retaining the valve stem in valveopen position. This electromagnet comprises a core MI and a winding I42.Cooperating with the core MI is an armature I44 carried by a lever I 45pivoted about a fixed pivot pin I46. A spring I biases the lever I45away from the electromagnet. Also secured to the pivot pin I46 is amember I41. A spring I48 is connected between the outer ends of memberI41 and lever I45 so as to tend to rotate member I41 clockwise withrespect to lever I45. Such clockwise movement is limited by a stop pinI49 carried by lever I45. Member I41 is thus connected to lever I 45through a strain release connection whereby the member I41 unlessotherwise restrained tends to rotate with lever I45. Carried at thelower end of member I41 is a projection I52 which is adapted to enter anotch I54 in the valve stem II8 when the stem is raised to substantiallyvalve open position.

Secured to the left hand end of lever I45 is a switch blade I58 which isadapted to cooperate with a fixed contact I51. The switch blade I56 andcontact I51 are employed for establishing a maintaining circuit to theapparatus as will be presently described.

An over center snap action switch is employed for controlling theenergization of the motor. This switch comprises a switch arm I60 and anarm I6I both pivoted about a pivot point I62. Connecting the two membersI60 and I6I is a spring I64. The switch arm I60 is adapted to engage acontact I65. The arm I6I is positioned by two arms I61 and I68projecting from valve stem II6. Asthevalve stem is moved upwardly, thearm I61 is effective to rotate arm I6I in a clockwise directionuntil'the arm I6I is aligned with arm I60. This portion of the movementis resisted by spring I64. As soon as arm I6I is moved farther however,it is past the "dead center position so that spring I64 is immediatelyeffective to continue the clockwise movement of arm I6I until it engagesthe upper arm I68 whereupon arm I60 is abruptly moved upwardly until itengages a stop pin I69. The switch arm H60 is thus separated fromcontact I65 with a snap action. The projecting arms I61- and I68 are sopositioned that this snap separation of switch blade I60 of contact I65takes place just as the valve reaches open position and at the time whennotch I54 is adjacent the projection I52 of member I41.

A thermostat I1I controls the operation of the valve. This thermostat isequivalent in function and in structure to thermostat 50 of the speciesof Figure 1. The thermostat comprises a bimetallic element I 12 to whichare secured contact arms I13 and I14. The bimetallic element iseffective upon a temperature drop to move contact arms I13 and I14'tothe left and upon a temperature rise to the right. Contact arms I13 andI14 are adapted to engage fixed contacts I15 and I16. The spacings ofthe contact arms I13 and I14 from contacts I15 and I16 are such thatcontact arm I13 is first engaged with contact I15 and contact arm I14 isthen engaged with contact I16.

A step down transformer I is employed for supplying low voltage power tothe motor and its control system. This transformer comprises a linevoltage primary I8I and a low voltage secondary I82. The line voltageprimary I8I is connected to a suitable source of power (not shown).

Operation of Figure 3 species The various elements are shown in theposition they assume when the temperature is at or above the desiredvalue. Under these conditions the valve is in its closed position. Upona temperature drop, contact arm I13 is moved into engagement withcontact I15 and upon a further drop, contact arm I14 is moved intoengagement with contact I 16. No energizing circuit is established untilcontact arm I14 engages contact I16. As soon as this happens, thefollowing energizing circuit is established to the field winding I22:from the right hand terminal of secondary I82 through conductor I83,contact I 15, contact arm I13, contact arm I14, contact I16, conductorsI85 and I86, field winding I22, conductor I81, contact arm I60, contactI65 and conductors I88 and I84 to the other terminal of secondary I82.The establishment of this circuit causes energiaztion of field windingI22 and rotation 01- the gear train in such a direction that gear I ismoved in a clockwise direction. As previously explained, this causes thepin I21 to engage with hook I28 and rotate lever I in a clockwisedirection. This movement of lever I30 results in valve stem II6 beingraised towards valve open position.

At the same time that the field winding I22 is first energized, acircuit is established to the winding I42 oi the electromagnet I asfollows: from the right hand terminal of secondary I80 through conductorI83, contact I15, contact arms I13 and I14, contact I16, conductors I85,I89, and I90, magnet winding I42 and conductors I9I and I84 to the otherterminal of secondary I82. The energization of electromagnet I40 resultsin the lever I being rotated in a clockwise direction. While movement ofmember I41 is impeded by reason of the fact that the projection engagesthe right hand edge of valve II 6 and is unable to enter the notch I54,

movement of lever I45 is still possible due to the strain releaseconnection between members I45 and I41. In other words, the lever I45 ismoved upwardly until the armature I44 engages the core I against theaction of spring I and spring I48 which urges the projection I52 againstthe edge of valve stem II6. Movement of lever I45 in the mannerdescribed results in the movement of switch blade I56 into engagementwith contact I51. As soon as such engagement takes place, a maintainingcircuit is established to the field winding as follows: from the righthand terminal of secondary I82 through conductor I83, contact I15,contact arm I13, bimetallic element I12, conductor I94, contact I51,switch blade I56, conductors I95, I89, and I86, field winding I22,conductor I81, switch arm I60, contact I65, and conductors I88 and I84to the other terminal of the secondary I82. At the same time amaintaining circuit is established to the magnet I42 as follows: fromthe right hand terminal of secondary I82 through conductor I83, contactI15, contact arm I13, bimetallic element I12, conductor I94, contactI51, contact arm I56, conductors I95 and I90, magnet winding I42 andconductors I9I and I84 to the other terminal of secondary I82.

The establishment of the two maintaining circuits just traced results inthe energization of the motor and of the electromagnet being independentof the engagement of contact arm I14 with contact arm I16. The advantageof this feature is the same as described in connection with Figure 1. Inother words, a differential is introduced into the operation to preventchattering or excessively frequent operations of the valve.

As the valve approaches open position, the notch I54 in the valve stemII6 comes adjacent the projection I52 of member I41. This member isforced into the notch by reason of the action of spring I48 which, aspreviously explained, has been placed under tension by movement of thelever I45 into the position in which the armature is engaged with theelectromagnet. Immediately after the projection I52 has entered thenotch I54, the arm I6I is moved beyond center with respect to arm I soas to cause these two arms to snap over center'thereby abruptlyseparating switch arm I 60 from contact I65. The separation of these twocontacts results in the interruption of both of the circuits to fieldwinding I22 previously traced. The motor is thus completely deenergizedso that biasing spring I 33 is now free to rotate lever I30 in acounter-clockwise direction. The biasing spring I33 is of such size thatit is able to rotate the gear train I25 and the motor rotor I2I in thereverse direction back to their original positions. Such return movementof lever I30 does not cause the valve to close due to the fact that thevalve stem is now latched in open position by the projection I52 ofmember I41 which extends into the notch I54. The movement of lever I30downwardly in a counter-clockwise direction, in spite of the valve stemII6 remaining in valve open position, is possible because of theelongated eye portion I34 which provides the connection between thelever I30 and the valve stem II6.

It will be seen that the lever I30 and the elongated eye portion I34 ofstem IIB constitute a pair of separable links, and that after lever I30is returned to the bottom of the eye portion I34 by the action of springI33, the links are separated in such a manner that the valve is free toreturn to its closed position upon release of projection I52 byelectromagnet I42.

The valve remains in its open position until contact arm I13 hasseparated from contact I15. When this happens, the electromagnet I40 isdeenergized so that the .lever I45 moves to the position shown in thedrawings in which the projection I52 is no longer in the notch I54. Thismovement of lever I45 is caused by not only the efiect of gravity on thelever but also by the biasing spring I50.

As with the species of Figures 1 and 2, it is assured that the valvewill always return to closed position in the event of power failureregardless of when such power failure occurs. Obviously such a powerfailure will result in the release of armature I44 so that the lever I45is ineffective to retain the valve in open position. If the powerfailure occurs before the projection I52 has entered the notch I54, thenthe valve is being held in open position only by the action of motorI20. Upon such power failure at this time, the spring I33 is efiectiveto return the transmission mechanism to its initial position and thevalve returns to its closed position by its own biasing means.

Whenever the valve stem returns to closed position, switch arm I60 issnapped back into engagement with contact I through the action of theprojecting arm I68. Switch blade I60 is thus again positioned inengagement with contact I65 so as to make possible the reenergization ofthe motor for the next operating cycle.

While the invention has been described in connection with valveoperators since this is the application for which it is most adapted, itis to be understood that the invention is applicable to the positioningof other devices movable between a safe position to which the device isbiased and a further active position. In general, while I have showncertain specific embodiments of my invention, it is to be understoodthat this is for purposes of illustration only and that the invention isto be limited only by the scope of the appended claims.

I claim as my invention:

1. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, electrically operated holding means for retaining said memberin said second position when an element associated with said member ismoved into cooperative relation therewith, motor means including auni-directional electric motor and a biasing means, means fortransmitting motion from said motor means to said member, a main controlswitch, switching means operable by said motor means and said member, asource of power, means controlled by said main control switch forconnecting said source of power to said electrically operated holdingmeans, and means controlled by said switching means operative to controlthe energization of said electric motor in such a manner that said motoris effective to move said element into cooperative relation with saidholding means and subsequently to drive said motion transmitting meansback to its original position, said biasing means being so connected tosaid motion transmitting means that in the event of power failure duringthe movement of said motor it is efiective to move said motiontransmitting means to a position wherein said member is free to move byits bias to said first position,

2. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, electrically operated holding means for retaining said memberin said second position when an element associated with said member ismoved into cooperative relation therewith, motor means including anelectric motor and a biasing means, means for transmitting motion fromsaid motor means to said member, a main control switch, a normallyclosed cycling switch, means for opening said switch when said member isin said second position and said transmission means is returned to saidoriginal position, a source of power, means controlled by said maincontrol switch for connecting said source of power to said electricallyoperated holding means, and a circuit for said motor including saidcycling switch operative to cause the energization of said rotaryelectric motor by said source of power until said element is moved intocooperative relation with said holding means and said motiontransmitting means is returned to its original position, said biasingmeans being so connected to said motion transmitting means that in theevent of power failure during the movement of said motor it is effectiveto move said motion transmitting means to a position wherein said memberis free to move by its bias to said first position.

3. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, electromagnetic holding means for retaining said member insaid second position when an armature associated with said member ismoved into cooperative relation therewith, a rotary electric motor;means for transmitting motion from said motor to said member, aconnection between said motion transmitting means and said memberpermitting movement of said motion transmitting means back to itsoriginal position without affecting the position of said member whensaid member is in said second position, a 'main control switch,switching means operable in accordance with the position of said member,a source of power, means controlled by said main control switch forconnecting said source of power to said tor by said source of power insuch a manner that said armature is moved into cooperative relation withsaid holding means and said motion transmitting means is then returnedto its original position.

4. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, electrically operated holding means for retaining said memberin said second position when an element associated with said member ismoved into cooperative relation therewith, motor means including arotary electric motor and a biasing means, means for transmitting motionfrom said motor means to said member, a connection between saidmotiontransmitting means and said member permitting movement of said motiontransmitting means back to its original position without affecting theposition of said member when saidmember is in said second position, amain control switch, switching means operable in accordance with theposition of said member, a source of power, means controlled by saidmain control switch for connecting said source of power to saidelectrically operated holding means, and means controlled by both saidmain control switch and said switching means operative upon closure ofsaid main control switch to control the energization of said rotaryelectric motor by said source of power in such a manner that saidelement is moved into cooperative relation with said holding means andsaid motion transmitting means is then returned to its originalposition, said biasing means being so connected to said motiontransmitting means that in the event of power failure during themovement of said motor it is effective to move said motion transmittingmeans to a position wherein said member is free to move by its bias tosaid first position.

5. In combination, a, member movable between a safe first position andan active second position, said member being biased to said safe firstposition, electrically operated holding means for retaining said memberin said second position when an element associated with said member ismoved into cooperative relation therewith, motor means including arotary electric motor and a biasing means, means for transmitting motionfrom said motor means to said member, a connection between said motiontransmitting means and said member permitting movement of said motiontransmitting means back to its original position without affecting theposition of said member when said member is in said second position, amain control switch, switching means operable by said motor means andsaid member, a source of power, means controlled by said main controlswitch for connecting said source of power to said electrically operatedholding means, and means controlled by both said main control switch andsaid switching means operative upon closure of said main control switchto cause said motor to be energized until it has moved said element intocooperative relationship with said holding means and has then drivensaid motion transmitting mechanism back to its original position, saidbiasing means being so connected to said motion transmitting means thatin the event of power failure during the movement of said motor it iseffective to move said motion transmitting means to a position whereinsaid member is free to move by its bias to said first position.

6. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, electrically operated holding means for retaining said memberin said second position when an element associated with said member ismoved into cooperative relation therewith, motor means including arotary electric motor and a biasing means, means for transmitting motionfrom said motor means to said member, a connection between said motiontransmitting means and said member permitting movement of said motiontransmitting means back to its original position without affecting theposition of said member when said member is in said second position,'amain control switch, switching means operated by said member, a sourceof power, means controlled by said main control switch for connectingsaid source of power to said electrically operated holding means, andmeans controlled by both said main control switch and said switchingmeans operative upon closure of said main control switch to cause saidmotor to be energized until it has moved said element into cooperativerelationship with said holding means and to deenergize said motorimmediately thereafter, said biasing means being effective upondeenergization of said motor at any time to return said motiontransmitting means to its starting position.

7. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, electrically operated holding means for retaining said memberin said second position when an element associated with said member is 2moved into cooperative relation therewith, motor means including anelectric motor and a biasing means, transmission means between saidmotor means and said member comprising a rotary cam driven by said motorand a cam follower associated with said member, said cam having asubstantial portion of its periphery of uniform radius and the remainderof gradually increasing radius, said uniform radius being of suchmagnitude that when the cam follower is in engagement with that portionof the cam, said member is maintained in said safe position by its bias,a main control switch, switching means operable by said movable memberand said motor means, a source of power, means controlled by said maincontrol switch for connecting said source of power to said electricallyoperated holding means, and means controlled by said switching meansoperative to control the energization of said electric motor by saidsource of power in such a manner that said element is moved intocooperative relation with said holding means and said transmission meansis then returned to its original position, said biasing means being soconnected to said transmission means that in the event of power failureduring the movement of said motor it is effective at all times to insurethat said cam is moved to a position wherein said cam follower engagesthe portion of said cam surface of uniform radius so that said member ismoved by its bias to said first position.

8. In combination, a member movable between a safe first position and anactive second position, said member being biased to said safe firstposition, a latch for retaining said member in said second position whenan element associated with said member is moved into cooperativerelation therewith, an electromagnet for moving said latch to itsoperative position, a switch positioned by said electromagnet, a

strain release connection between said latch and said electromagnet sothat upon energization thereof said electromagnet can assume itsenergized position and position said switch even though said element isnot in cooperative relation with said latch. an electric motor formoving said member to said second position, a main control switch,switching means operable by said movable member, a source of power,means controlled by said main control switch for connecting said sourceof power to said electromagnet to cause said electromagnet to bias saidlatch ta its operative-position and to position its associated switch,and means controlled by said electromagnet switch and said switchingmeans for causing the energization of the motor to move' said elementinto cooperative relation with said latch and thereafter deenergizingsaid motor.

9. In combination, a member biased to a first position, a latch'forretaining said member in a second position when a shoulder portion oisaid member is moved adjacent said latch, an electromagnet for movingsaid latch to its operative position, a switch positioned by saidelectromagnet, a strain release connection between said latch and saidelectromagnet so that upon energization thereof said electromagnet canassume its energized position and position said switch even though saidshoulder is not adjacent said latch, an electric motor for moving saidmember to said second position, a main control means under the controlof said main control switch for energizing said electromagnet to causesaid electromagnet to bias said latch to its operative position and toposition its associated switch, switching means operated by said member,and means controlled by both said electromagnet switch and saidswitching means operative as a result of closure of said main controlswitch to cause energization of the motor until said shoulder portion isengaged by said latch and thereafter to deenergize said motor.

10. In combination, a member movable between a first position and asecond position, means biasing said member to said first position,electrically operated means for holding said member in said secondposition against the action of said biasing means, motor means includingan electric motor and a second biasing means, means for transmittingmotion from said motor means to said member, a connection between saidmotion transmitting means and said member permitting movement of saidtransmitting means back to a position corresponding with the firstposition of said member while said member re mains in its secondposition, a first switch, a second switch operable in accordance withthe position of said member, an energizing circuit for said holdingmeans. an energizing circuit for said motor, and means including saidcircuits controlled by said switches and operative upon closure of saidfirst switch to cause said motor means to move said transmitting meansand hence said member from first to second position and then to returnonly said transmitting means to its position corresponding to the firstposition of said member said second biasing means being so connected tosaid motion transmitting means that in the event of power failure duringthe movement of said motor it is effective to move said motiontransmitting means to a position wherein said member is free to move byits bias to said first position.

11. In combination, a member movable between a first position and asecond position,

means biasing said member to said first position, electrically operatedmeans for holding said member in said second position against the actionof said biasing means, motor means including an electric motor and asecond biasing means, means for transmitting motion from said motormeans to said member, a connection between said motion transmittingmeans and said member permitting movement of said transmitting meansback to a position corresponding with the first position of said memberwhile said member remains in its second position, a first switch, asecond switch operable in accordance with the relative positions of saidtransmitting means and said member, an energizing circuit for saidholding means, an energizing circuit for said motor, and means includingsaid circuits, controlled by said switches and operative upon closure ofsaid first switch to cause said motor means to move said transmittingmeans and hence said member from first position to second position andthen to return only said transmitting means to its positioncorresponding to the first position of said member said second biasingmeans being so connected to said motion transmitting means that in theevent of power failure during the movement of -said motor it isefiective to move said motion transmitting means to a position whereinsaid member is free to move by its bias to said first position.

12. In combination, a member movable between a, first position and asecond position, means biasing said member to said first position,electrically operated means for holding said member in said secondposition against the action of said biasing means, motor means includingan electric motor and a second biasing means, means for transmittingmotion from said motor means to said member, a connection between saidmotion transmitting means and said member permitting movement of saidtransmitting means back to a position corresponding with the firstposition of said member while said member remains in its secondposition, a first switch, a second switch operated by said member, anenergizing circuit for said holding means, an energizing circuit forsaid motor, and means including said circuits controlled by saidswitches and operative upon closure of said first switch to cause saidmotor means to move said transmitting means and hence said member fromfirst position to second position and then to return only saidtransmitting means to its position corresponding to the first positionof said member said second biasing means being so connected to saidmotion transmitting means that in the event of power failure during themovement of said motor it is effective to move said motion transmittingmeans to a position wherein said member is free to move by its bias tosaid first position.

13. In combination, a member biased to a first inactive position,holding means for retaining said member in a second active position whenan element associated with said member is moved into cooperativerelationship therewith, a rotary electric motor, means for transmittingmotion between said motor and said member, a main control switch, asecond switch operable in accordance with the position of said member,and a single energizing circuit including said motor controlled by saidswitches and operative upon closure of said main control switch to causemovement of said member from first to second position, thereby movingsaid element into cooperative relationship with said holding means, andthen to cause movement of said motiontransmitting means to a positioncorresponding to the first position of said member.

14. In combination, a member biased to a first position, anelectromagnet for retaining said member in a second position when anarmature connected to and movable with said member is moved intoengagement with said eloctromagnet. an electric motor, means fortransmitting motion from said motor to said member, a connection betweensaid transmitting means and said member permitting movement of saidtransmitting means back to its original position while said memberremains in its second position, a main control switch, a second switchoperable in accordance with the position of said member, and a singleenergizing circuit including said motor controlled by said switches andoperative upon closure of said main control switch to cause movement ofsaid member from first to second position, thereby moving said armatureinto engagement with said electromagnet, and then to cause movement ofsaid motion-transmitting means to a position corresponding to the firstposition of said member.

15. In combination, a member biased to a first position, electicallyoperated holding means for retaining said member in a second positionwhen an element associated with said member is moved into cooperativerelationship with said holding means, an electric motor, means fortransmitting motion from said motor to said member, a connection betweensaid transmitting means andv said chamber permitting movement of saidtransmitting means back to its original position while said memberremains in its second position, a main control switch, a second switchoperable in accordance with the position of said member, and a singleenergizing circuit including said motor controlled by said switches andoperative upon closure of said main control switch to cause movement ofsaid member from first to second position, thereby moving said elementinto 00-- operative relationship with said holding means, and then tocause movement of said motiontransmitting means to a positioncorresponding to the first position of said member.

ROBERT S. CRAIG.

